Helicopter images showed all seven cars and the locomotive pushing the Metro-North train derailed — at least two of them were thrown on their side. The leading car came within feet of plunging into the Harlem River.

NBC New York reports that the transit agency tells them the train left at 5:54 a.m. from Poughkeepsie and was due in Grand Central Terminal in Manhattan at 7:43 a.m. ET.

Reporters and eyewitness at the scene said they heard a loud screech before the crash. One neighbor who NPR member station WNYC's Brigid Bergin spoke to said the sound was so loud, he thought it was a nearby bridge collapsing.

Another witness told ABC New York that when first responders arrived on the scene, they smashed the windows of the railcars to extricate passengers.

During a press conference, New York Gov. Andrew Cuomo said four people had died and 63 were injured. Fourteen of those are in critical condition. Cuomo and MTA officials said it was too soon to know what caused the crash.

The Wall Street Journal reports that the speed limit at the curve where the train derailed is 30 miles per hour. It isn't clear, however, "how fast the train was traveling when it derailed, Metro-North spokeswoman Marjorie Anders said."

This is a breaking news story, we'll update this post with the latest as we get it.

Update at 4:54 p.m. ET. All Seven Cars, Locomotive Derailed:

During a televised press conference, Earl Weener, of the NTSB, said that all seven cars, plus the locomotive had derailed during the incident.

Weener said it was too early to tell whether speed was a factor, as some witnesses had indicated, and whether human error or mechanical failure was at fault for the crash.

The NTSB will now turn the overturned cars upright to check for any survivors and once they are done collecting evidence, they will allow the Metropolitan Transit Authority to begin their clean up.

New York Gov. Andrew Cuomo said New Yorkers in that area should expect a rough commute tomorrow morning. Cuomo reiterated that the MTA is cooperating with the NTSB and is looking forward to their findings.

"Safety is job one," Cuomo said.

Update 1:24 p.m. ET. Other Accidents:

In an interview with CNN, NTSB Chairman Deborah Hersman said the agency will be looking closely at "several incidents that have occured on Metro-North's property over the past 8 months."

Hersman said that they will look closely at a trash train that derailed near that same section in July and they will also look closely at a number of repairs Metro-North has been making on the rail line.

"Joel Zaritsky had just fallen asleep in the fourth car of the train when the train started to roll over and landed almost on its side, he said.

'People were screaming,' he said on Sunday morning as he was traveled to the hospital. 'I found myself thrown to the other side of the train.'

"Mr. Zaritsky, who lives in Poughkeepsie, and was heading to New York for a convention, said his hand was cut and he was very bruised.

"'I still can't believe it,' he said. 'I'm very happy to be alive.'"

Update at 10:52 a.m. ET. Conductor In Hospital:

During a televised press conference minutes ago, New York City Police Commissioner Ray Kelly said the train's conductor is in the hospital and in stable condition.

Kelly said he would not go into what the conductor had told them and that this was now an NTSB investigation.

Kelly said first responders had combed the area for victims with cadaver dogs and divers and they are pretty certain that no one remains in the wreckage.

Update at 10:23 a.m. ET. 4 Dead:

During a press conference, New York Gov. Andrew Cuomo said four people had died and 63 were injured. Eleven of those are in critical condition. Cuomo and MTA officials said it was too soon to know what caused the crash.

One bit of good news is that Cuomo said authorities believe everyone has been accounted for at the scene, so the number of injuries is unlikely to rise.

Separately, the National Transportation Safety Board said it was sending its "go-team" to New York to investigate the accident."

WABC-TV is reporting that there at least 30 injured. NBC News is reporting that number at 48.

We're expecting a press conference by the New York Fire Department shortly.

Update at 8:40 a.m. ET. Injured Being Pulled Out On Stretchers:

WABC-TV spoke to a passenger who was riding on the first car of the derailed train. He told the station that he was able to get off the train on his own, but others were not that lucky and were being extricated by emergency workers.

A reporter on the site for the station, said he saw emergency workers smashing windows and removing passengers in stretchers.

Images taken from above the crash show 7 cars of the Metro-North train derailed. The first one came very close to hitting the water.